Formation of an active surface on oxide systems containing vanadium used for dehydrogenation of hydrocarbons in the presence of hydrogen acceptors. 4. Catalytic and physicochemical properties of vanadium-zirconium and vanadium-titanium catalysts for the oxidative dehydrogenation of ethylbenzene in the presence of nitrobenzene

Abstract

A study has been made of the catalytic and physicochemical properties of vanadium-zirconium and vanadium-titanium oxide systems in the oxidative dehydrogenation of ethylbenzene in the presence of nitrobenzene. The degree of conversion to styrene was less than 10% and to aniline 60%. The methods used to study the physicochemical properties of the catalysts were diffuse reflection electron spectroscopy (DRES), x-ray and differential thermogravimetric analysis. The presence of surface VTd5+, VOh5+, and VQ4+ ions has been established, their ratios depending on the initial vanadium concentrations, the nature of the carrier, and the thermal treatment conditions. In the vanadium—zirconium systems VTd5+ predominate, but in the vanadium-titanium ones VQ4+. The VOh5+ ions appear to be present in the form of clusters. A chemical compound between the active components and ZrO2 and a V2O5 phase have been detected, which take no part in the dehydrogenation reaction.